Book/Dissertation / PhD Thesis

FZJ-2019-01707

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Quantitative Analyse der Trocknungsverläufe von Katalysatordispersionen

Scheepers, F. (Corresponding author)FZJ*

2019
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-384-6

Please use a persistent id in citations: http://hdl.handle.net/2128/22006  urn:nbn:de:0001-2019040116

Abstract: The production of electrodes for their application in electrolyzers and fuel cells is based on the production of a catalyst-containing, aqueous-alcoholic dispersion. This is processed into a wet layer which, finally, forms the electrode. Many processes before and after the coating are well studied. There is no doubt about the continuous change in the chemical and physical properties in the layer. However, the drying process of the wet layer produced is rarely documented in the literature. This work focuses on the design, development and characterization of a first tool to analyze the chemical composition during the drying process. To quantify the measurement uncertainty statistical methods were used. The calculated standard uncertainty was confirmed experimentally to be less than one percent for most drying trials. The comparison with methods from the literature shows that the developed system has the highest accuracy for chemical analysis in the field of drying. The method was used to correlate the drying process and the cracking of layers. The produced layers showed an increasing amount of cracks when water accumulation occurred in the course of drying. The crack formation is not examined in this work for its electrochemical importance but described as an observation only. Based on this, parameters were varied in order to influence the drying process in a substance-specific manner. The results showed by which the drying selectivity is influenced, meaning the enrichment or depletion of single solvents. For catalyst-containing, aqueous-alcoholic dispersions it was found that avariation of the water content reverses the selectivity without changing significantly the drying behavior of alcoholic solvent content. It was found that the interactions between dispersion and substrate do not influence the drying process but result in different cracking behavior. This is related to the surface energy of various substrates. The drying of dispersions under air atmosphere resulted in a significant occurrence of oxidation products in the sample. The reversal of the drying selectivity in the end of the drying signaled a depletion of alcoholic content in the residual solvent of the dispersion. The present work confirms that the theoretical models for drying are basically transferable to electrode drying. In accordance with models, a strong dependence of thedrying selectivity on the overflow rate and the partial pressure of solvents in the dryinggas were found. As expected, changes in the drying temperature showed an unselectiveeffect on the drying. The three parameters mentioned before act on the total drying timein combination

Note: RWTH Aachen, Diss., 2018

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Contributing Institute(s):

1. Elektrochemische Verfahrenstechnik (IEK-3)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2019

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